In an image scanning system, a beam of light is typically scanned across a target area and the backscattered or reflected light is modulated in intensity and color to give a pixel at the particular location and time within the scan corresponding to the point on the surface. To increase image resolution or decrease the size of the image pixel, the optical point of interrogation on the surface need to be made sufficiently small. However, when the light is focused to a small spot, the depth of focus or depth of field of the resulting image becomes relatively shallow as well, meaning that only a small portion of the target area remain in focus. There is a need, therefore, to provide an extended depth of focus or field while maintain high image resolution.